Fluid sampling system



9% 269 1943- J, APELLETTERE FLUID SAHPLING SYSTEM Filed No'v. 25. 1947 z -zaficnmssuzm REGULTOR WGUJATED :AIR suma Pstented Oct. 26, 1948 Aria OFFHC FLUID SAMPLING SYSTEM Application November 26, 1947, Serial No. 788,216

9 Claims. (Cl. 73-4215) This invention relates to a fiuid sampling system and more particularly to a gas sampling system which is `capable of collecting a composite gas sample from ,a closed line in proportion to the fiow in that line.

The principal object accomplished by my invention is the provislon of a device to accumulate a representative sample from a stream of gas of varying composition and of varying rate of flow.

Another object accomplished by my invention is the provision of a fiuid sampling s'ystem which will, over a period of time, incrementally accumulate a composite gas sample Ifrom a conduit in direct proportion to the-volume of gas fiowing therethrough. v

A further object accomplished by my invention is the provision of a gas sampling system incorporating practical design and simple operational features therein so as to'require a minimum of attention during sampling.

Other objects will appear hereinafter.

In the conduct of chemical processes it is often necessary or desirable to accumulate a representative gas sample, that is, a sample composed of equal increments for each unit volume of gas passing through a Conduit, irrespective of variations in velocity of flow through the conduit. The problem of collecting such a sample is a relatvely simple one where the gas fiow and gas pressure remain substantially constant in the line from which a sample is desired. On the other hand, when the gas is subject to frequent .variations in composition, pressure, and rate of flow, as is often the case in petroleum refinery Operations, and particularly in pilot plant operations. the taking of representative gas samples involves a rather difficult problem. This is more apparent when it is understood that a composite sample must be accumulated of increments taken intermittently over a period of time to be truly representative of the yield of a continulng operation. I have found that where the rate of fiow, the pressure and the composition `of the gas are varying from moment to moment, common gas sampling devices do not gather successlve increments that are truly proportional to the quantity of gas fiowing in the line that is being sampled.

The invention is particularly advantageous in that it provides a sampling system that will collect over any desired period of time a sample which is truly representative of the average composition of the fluid flowing through a line during that period. Another advantage is the adapt- .ability of the inventlon the sampling of comgenerally regarded as hazardous where the use of sampling devices essentially of an electrical nature is contemplated. However, the utiliza-. tion of a pneumatlc control system in the eml bodiment of my invention here shown and'tdescribed substantially eliminates any danger of fire or explosion. Further advantages appear in the novel construction and arrangement of the component parts ofl the system and the flexibility resulting therefrom.

My invention is exemplifled by the accompanying Figures 1 to 4, inclusive, a description of which follows:

Fig. 1 ls an isometric view lof one embodiment of my sampling system.

Fig. 2 is a vertical Sectional view of pilot valve 5 and 'its connection when a periodic sample is being taken.

Fig. 3 is a vertical Sectional view of pilot valve 5 when no sample is being taken.

Fig. 4 is a vertical Sectional view of fluid operated power unit 4 and its associated mechanism.

Fig. 1 shows the entire device, and comprises as the principal elements a gas line I and 2, a

gas meter 3, fiuid operated power unit 4, pilot valve 5, gas holder 6, back pressure regulator l, and various interconnecting lines as shown. The gas, a portion of which it is desired to obtain as a sample, fiows through'lines I and 2 in which is interposed gas meter 3. meter has fan integrating mechanism 8 and the shaft of this Integrating mechanism carries an extension 9 fitted with a cam IG.

Fluid operated power unit ll comprises a flexible diaphragm II mounted within a chamber I2. A fiuid pressure line 93 connects to the upperI side of the diaphragm II and displacement of the diaphragm by pressure on the upper side is resisted by spring M on the lower side thereof. Attached to the lower side of the diaphragrn II is stem l guided at its lower end by guide-piece IG. The vertical movement of stem I5 is limited by an adjustable stop I'l in the base of guide-piece iii. Connected to stem Iiis lever I8 fulcrumed at IS and carrying on its outward extremity pawl 20. When the pressure of the fluid in line I3 operates on diaphragm II it forces that diaphragm downward against the resisting pressure of spring It. This downward motion of' diaphragm I I carries with it the attached stem I-. At the same time the end of lever IB attaohed to stem l is forced downward and, due

The gas to its being fulcrumed at IG. the outer end of lever I8 moves upward. In moving upward. the

pawl 20, carried on the end of lever IB. effects f partial rotation of ratchet 2I. When pressure is released on diaphragm Il, the spring I4 causes upward motion of diaphragm I I, stem I5 and the attached end of lever i8. The resulting retreat of pawl 20 from ratchet 2I does not result in counter rotation of ratchet 2! due to the operation of pawl 22. The rising motion of stem t5 lowers the position of pawl 20 and positions it against a subsequent tooth of ratcheiI 2! thereby placing it in position to further rotate ratchet `2I the next time diaphragm il and stem li are forced downward. A sprocket wheel 23 is mounted on the same shaft as ratchet 2!, and both ratchet and sprocket arev permanently fastenedto the shaft so that the rotation of the ratchet will be transmitted to the sprocket.

A base 6 and bell 23 form a conventional liquidsealed gas-holder to receive the -desired sample of gas. gressively by chain 25 which passes over the previously described sprocket Wheel 23 and is balanced by a counter-weight 26.

The purpose of this device is to't'ake a small sample of gas from gas-line 2 through line 21 into gas-holder 24 each time a previously determined quantity of gas is passed through gas meter 3. To accomplish this purpose a pilot valve 5 is provided to alternately pass and interrupt the stream of fluid under pressure lsupplied through line i3 to the upper side of diaphragm II of the fluid operated power unit 4. The frequency of passing and interrupting the energizing fiuid to the upper side of the diaphragm is determined by the number of nodes on the periphery of a cam Ill attached to integrator 8 of gas meter 3. If the flow integrator 8 were required to carry the full power load of opening and breaking the fluid supply in line l3, it would seriously interfere with the accuracy of gas meter 3 and therefore the pilot valve 5, in combination with cam I ls designed to put no substantlal load on meter integrator 8 in 'rotating cam I0. Pilot valve is a pneumatically operated pilot valve that not only interrupts and opens the supply of energizing fluid to fiuid operated power unit 4, but also is itself operated by the same supply of gas under pressure. This gas may advantageously be air, although, if the pressure be adequate, it may be gas from line 2. The heart of the pilot Valve is a light metallic bellows 28 of the Sylphon type. Referring to Figs. 1, 2 and 3, it will be noted that when the face of cam Io is away from nozzle 29, the pneumatie pressure in line 30' causes a restricted flow through orifice 3| and line 32. The openings in oriflce 3I and nozzle 29 are so proportioned that discharge of gas through nozzle 29 will prevent the accumulation 'of any substantial pressure in line 32 and the inside of connected bellows 28. Therefore, when the face of cam Hl is removed from nozzle 23, as shown in Figs. 1 and 3, bellows 28 assumes its naturally contracted position in Fig. 3. connected to the upper end of. bellows 28 is Valve stem 33 carrying cut-offs 34 and 35. It will be observed from Fig. 3 that when'nozzle 29 is opened by removal therefrom of cam IO, Valve cut-off element 35 will prevent the passage of pressure fluid from inlet port 36 to the power unit through line I3, and by depressing the position of cut-off 35 will permit the escape of fluid pressure from the upper side of power unit diaphragm H through line I3 and escape port 31 to the atmosphere. When integrator 8 brings cam Il) into The bell 24 of the gas-holder is raised proe 'the position shown in Fig. 2, the cam comes within say 0.00l of an inch or 0.002 of an inch of nozzle 29. substantlally closes the' nozzle 28 and causes the fluid pressure in line- 32 to rise to a pressure closely approaching that in line 30. This increased pressure in line 32, communicationr through orifice 38 to the inside of bellows 28. causes expansion of bellows 28. That expansion of bellows 28 raises valve stem 33 to the position shown in Fig. 2 and it will be noted that in such position cut-off eiement closes the connection between line I8 and discharge port 81. and simultaneously opens the pressure line from line through 38 to line |3 and the upper side of diaphragm i i of fiuid operated power unit A back pressure regulator 'l is positioned in main gas line 2 and maintains a uniform pressure in sampling line 21 and gas-holder 8.

Operation of the sampling device includes the following sequence of operations. The gas-holder bell 24 is completely lowered into its base 8 so that no gas is contained therein. Depending upon conditions of the gas in main 2 and the particular requirements of the operator, the size of sample increments may be varled by adiusting screw Il in the base of the fluid operated power unit 4. The gas stream from which a sample is to be taken, upon fiowing from main i through meter 8 and through main 2, will effect the operation of meter integrator 8, in accordance with the volume of gas passing through the meter. The shaft extension 8 of the integrator, and cam ID which is afflxed thereto. will rotate accordingly in direct proportion to the gas fiow. This rotation of cam I0 will, once during each revolution thereof, restrict the discharge of air from nozzle 29 of pilot Valve 5, and cause the bellows 28 to expand under a gas pressure of say l or 2 pounds exerted through passage 38 into the bellows. Valve stem 33 will then become elevated, carrying its cut-off element 35 above the passage to line l3 .as shown ln Fig. 2, thereby permitting the passage of pneumatic power from line 30 through line 36. the valve and line I 3 to fluid operated v power unit 4. The cut-ofi' element 34 on valve stem 33 merely serves as a seal to prevent the discharge of air from the passages of the valve 5 past the movable vaive stem 33 to the lower portion of the valve. Transmission of power fluid to power unit 4 results in the depression of diaphragm II, and drive stem IS, which, through fulcrumed lever I8 and pawl 20, effects the partia] rotation of ratchet wheel 2I, the degree of rotation depending on the position of the stroke acliusting screw member I'I. As a consequence. sprocket 23 carrying sprocket chain 26 with it will experience the same degree o: rotation and cause the bell 24 of the gas sample holder to be raised a predetermined distance. Gas from main 2 will then be drawn through sampling line 21 into the bell of sample holder 6. To assure the obtaining of equal increments of gas with each rise of bell 24, back pressure regulator 'I is installed in gas main 2 to maintain substantialiy constant pressure at the sampling point.

When the node of cam Ill passes beyond the V .nozzle 29 of pilot valve5. the pilot Valve will return to closed position which is the condition of the valve during the greater part of the rotation of cam HI, as shown in Fig. 3. The nozzle 29, being no longer restricted by the cam, will again discharge air freely, preventing the building up of pressure within the bellows 28 and permitting the bellows to return to its normal contract-.ed position. This contra'ction causes pilot valve stem 38 to recede to the point where cut-off element 35 blocks the p'assage of pneumatic power through the valve 5 to line IS. Itxfurther permits the air under pressure above diaphragm II of power-'unit d to' dlscharge through line [3 and exhaust port 31 of the pilot valve 5 .into the atmosphere. The return of atmospherlc pressure above the diaphragm II permits the spring H to elevate the diaphragm II and drive stem 'l to their normal positions. This also causes pawl 20 to sllp on ratchet wheel 2| and take a new position ready to again effect partial rotation of ratchet 2| on the next movement of the diaphragm. The ratchet wheel 2I will not move backward at this time due to the restrlcting eflect of pawl 22.

Thus each time the cam IO completes a revolution restrictlng nozzle 29, the sprocket-wheel 23 rotates ln measured degree and gas holder bell 24 moves upward a certain predetermined distance causing a quantity of gas to pass from gas main 2 through sampling line 29 into the gas sample holder 24. When the node of cam III has passed beyond nozzle 29 of the pilot valve, free discharge through nozzle 29 will be resumed and the flow of energizing fluid to power unit 4 will be discontlnued.

'To collect a sample over a' period of time, the

node of cam IO will pass the nozzle of. pilot valve 5 a multitude of times and gas sample' holder bell 24 will be raised each time to receive successive increments of gas from gas main 2. Therefore, the sequence of Operations described in detail above will be repeated many times during the process of obtaining a sample, according to the length of time over which the sample is gathered.

Many modifications of the abov described invention may be embodied and many equlvalents, vof the respective elements of the sampling system may be used without departing from the spirit and scope of this invention. For. example, instead of using an external air supply for actuating the control mechanism, if the fluid to be sampled is a gas, valve 39 in connecting line 40 may be opened. and valve Ill in line 30 closed to provide a passage for a pressure controlled pneumatic power medium from main conduit 2 to pilot valve 5. On the other hand, if an external source of pneumatic power is to be used, valve M would be opened and valve 39 closed. A

This inventon is especially adaptable for obtainingi a sample under law pressure, that is a pressure of less than one pound' per square inch, gauge, but it may also be readily used with gas of a much greater pressure either by placing a pressure. reducing valve in sampling'line 27 from main 2 to gas-holder 6 or by designing the gasholder with its weight so proportioned to its cross section that. the bell 2d will not be blown out of base 6.

' I claim.:

`i. A device for incrementally accumulating a composite sample of gas from a flowing stream thereof comprising a gas conduit adapted to convey a flowing stream of gas, pressure'regulating means to maintain substantially uniform pressure in said gas conduit, a meter interposed in said 'gas conduit, a gas holder to receive the desired sample, a sampling tube connecting said gas conduit and said gas holder, a power unit adapted to increase the capacity of said gas holder by a fixed increment at each actuation of the power unit, a pilot valve to supply energizing force to the i said power unit and means operatively controlled by the said meter to actuate the pilot valve each time a predetermined volume of gas passes through the said meter.

2. A device for incrementally accumulating a composite sample of gas from a flowing stream thereof comprising a gas conduit adapted to convey a flowing stream of gas, pressure regulating means to maintain substantially uniform pressure in said gas conduit, a meter interposed in said gas conduit, a gas holder to receive the desired sample, a sampling tube oonnecting said gas conduit and said gas holder, a pneumatically operated power unit adapted to periodically increase the capacity of said gas holder by a fixed increment at each actuation of the power unit, a pneumatically operated pilot valve to supply energizing force to the said-power unit, and means operatively controlled by the said meter to actuate the pilot valve each time a predetermined volume of gas passes through the said meter.V

3. A device for incrementally accumulating a composite sample of gas from a flowing stream thereof comprising a gas conduit adapted to convey a flowing stream of gas, pressure regulating means to maintain substantially uniform pressure' in said gas conduit, a meter interposed in said gas conduit and fitted with a shaft rotatable ln direct proportion to the volume of gas passed therethrough, a gas holder to receive the desired -sample. a sampling tube connecting said gas conduit 30 and said gas holder, a power unit adapted to increase the capacity of said gas holder'by a flxed V power unit, and means comprising a cam attacbed to the said meter shaft to actuate the pilot valve each time predetermined volume ofgas 'passes through the said meter.

i said gas conduit and provided with an integrator having an'extended shaft which rotates in direct proportion to the volume of gas passed therethrough, a gas holder to receive the desired sample, a sampling tube connecting said gas conduit and said gas holder, a power unit adapted to increase the capacity of said gas holder by a fixed increment at each actuation of the power unit, a pilot valve to supply energizing force to the said power unit, and means comprising a cam attached to the said meter integrator shaft to actuate the pilot valve each time a predetermined volume of gas passes through the said meter.

5'. A device for incrementally accumulating a composite sample of gas from a flowing stream thereof comprising a gas conduit adapted to convey a flowing stream of gas, pressure regulating Vmeansto maintain substantially uniform pressure in said gas conduit, a meter interposed in said gas conduit and fitted with a shaft that rotates in direct proportion to the volume of gas passedV therethrough, a gas holder to receive the desired sampleLa sampling tube connecting said gas conduit and said gas holder, a pneumatically operated powerfunit adapted to increase the capacity of said. gas holder by a fixed increment at each actuation of the power unit, a pneumatically pilot valve-each time a predetermined volume of .gas passes through the said meter.

V` means to maintain substantially uniform pressure insaid gas conduit, a meter interposed in said gas conduit and provided with an integrator having an extended shaft. which rotates ln direct proportion to the volume of gas passed therethrough, a gas holder to receive the desired sample. a sampling tube connecting said gas conduit and said gas holder, a .pneumatically operated power unit adapted to increase the capacity of said gas holder by a flxed increment at each actuation of power unit, a pneumatically operated pilot valve to supply energizing force to the said power unit. and means comprising a cam attached to the said meter integrator shaft to actuate the pilot valve each time a predetermined volume of gas passes through the said meter.

7. A device for incrementally accumulating a composite sample of gas from a flowing stream thereof comprising a gas condult adapted to convey a fiowing stream of gas, pressure regulating means to maintain substantially uniform pressure in said gas conduit, a meter interposed in said gas conduit and provided with an integrator havingan extendedshaft which rotates in direct proportionto the volume of gas passed thereitii'roughgam trpe gas holder to receive the desired sample. a; sampling-tube connecting saidv gas conduit and said gas holder, a pneumatically operated power unit adapted to periodically increase the capacity of said gas holder by a fixed vincrenrent 'at'each actuation of the power unit,

a pneumatically operated pilot valve to supply energizing force to the said power unit, and means comprising a cam-attached` to the said meter integrator shaft to periodically actuate the pilot valve in proportion to the flow of gas through the said meter. 4

8. A device for incrementally accumulating a composite samplezof gas from a flowing stream thereof comprising a gas conduit: a pressure regulator adapted to maintain uniform pressure in cordance with the flow of gas through said meter.

8 said gas conduit; a gas ga's conduit and fltted with a shaft adapted to rotate with a frequency proportioned't'o the volume of gas passed through said meter; a gas holder to receive a proportioned sample of gas; a second conduit extending from the first mentioned conduit to the gas holder; a pneumatically energized power unit, connecting means for enlarging the capacity of the gas holder with each energlzation of the said power unit; a third conduit to conduct a gas to the power unit to energize the same; a pilot valve interposed in the third mentioned conduit and adapted to alternately permit and interrupt the flow of energizing fluid therethrough, and to relieve the pressure of such energizing fluid on the said power unit when the pilot Valve is in position to interrupt the flow thereof; andmeans fltted on the rotating shaft of the gas meter and serving to actuate the pilot valve. V'

9. A gas sampiing system comprising, a gas main, means for maintaining substantially uniform pressure in said gas main, a gas meter interposed in said gas main, a gas sample holder, connecting means between said gas main 'and said sample holder. fluid operated means to vary the capacity of said sample holder, control means for supplying operating fluid to said last named means, and means operatively controlled by said meter for energizing said control means in ac- JOSEPH A. PELLETTHE.

REFERENcEs crrap The following references are of record in the file of this patent:`

UNITED STATES PATENTS Grace, Jr. Apr. 15,

meter interposed in saidl 

